HR: 09:30h
AN: A11E-06    [Abstracts]
TI: The Solar Cycle Variation of Stratospheric Ozone: An Observational Update and Model Comparisons
AU: * Hood, L L
EM: lon@lpl.arizona.edu
AF: Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721-0092 United States
AU: Soukharev, B E
EM: boris_soukharev@hotmail.com
AF: Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721-0092 United States
AU: McCormack, J P
EM: mccormack@nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 United States
AB: The observed solar cycle variation of ozone is a key constraint on climate models that include solar UV / ozone / dynamical coupling as a sun-climate forcing mechanism. Standard multiple regression statistical models have previously been applied to estimate the solar cycle component of stratospheric ozone variability using long-term satellite ozone profile data sets (SBUV(/2) over the 1979 to 1994 time period and SAGE II over the 1984 to 1998 time period). These analyses indicate that (a) the largest percentage ozone increase from solar minimum to maximum is in the upper stratosphere (1-3 hPa); (b) a minimum percentage increase occurs in the tropical middle stratosphere (5-10 hPa); and (c) a larger percentage increase occurs in the tropical and subtropical lower stratosphere, which is mostly responsible for the solar cycle variation of total ozone. This observationally derived altitude dependence in the middle and lower stratosphere differs from the predictions of radiative-photochemical models for the solar UV induced ozone response over a solar cycle; the latter predict a maximum ozone increase in the middle stratosphere (about 5 hPa) and a small or negligible increase in the lower stratosphere. An important unresolved issue is whether interference from decadal changes in the QBO wind field or major volcanic aerosol injections (occurring following solar maxima in 1982 and 1991) may have been partly or entirely responsible for the unexpected altitude dependence derived from observations. Here, we report analysis of the Version 8 SBUV(/2) ozone profile data set extending from 1979 to 2003 (NASA Ozone Processing Team, http://code916.gsfc.nasa.gov/Data\_services/). This time period includes most of solar cycle 23 during which there was no major volcanic eruption. Results continue to show that the ozone solar cycle variation in the low-latitude middle stratosphere (5 to 10 hPa) is very small or negligible. Comparisons are made with model simulations using the NRL CHEM2D model to investigate whether interference from the QBO (which is interactive in the model) can explain this unexpected altitude dependence. Comparisons are made between statistical results for solar cycle 23 and the previous two cycles to evaluate whether interference from volcanic aerosols can explain the altitude dependence.
DE: 1650 Solar variability
DE: 0340 Middle atmosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting